PSI - Issue 1

A. C. Ferro et al. / Procedia Structural Integrity 1 (2016) 249–256 Author name / Structural Integrity Procedia 00 (2016) 000 – 000

251

3

(d)

(a)

(c)

3

20 mm

2

(b)

1

Fig. 1. (a) original U-bolt stirrup; (b) fractured U-bolt stirrup; (c) overhead line on the ground floor after stirrup rupture; (d) support system composed by U-bolt stirrup (1), lifting eye (2) and ball socket (3).

mechanisms responsible for the collapse of the structure. Cross sections were polished and some etched with Nital 3%. Residual resistance of the broken U-bolt stirrup and was evaluated via dedicated designed tensile testing (Instron 250 kN tensile testing machine) and compared with the original steel component specification. The load capability of the support system using S-Nw was also tested. Fig. 2a shows the zones of the S-Nw where samples were collected for analysis of the original steel quality, of the galvanized coating as well as changes induced by the manufacturing process. Two zones were chosen: one to study the transversal cross section, S-Nw/tcs , and another to study the longitudinal cross section, S-Nw/lcs . Fig. 2b shows the method used to collect the samples to study the fracture process of the S-Fr . Two samples were collected: one of the fracture surface, S-Fr/FS , and another to study its cross section, S-Fr/FS/cs . The chosen cross section is longitudinal to the original stirrup bar and contains the direction of the overhead cable (considered perpendicular to

tcs

(a)

(b)

i

ii

lcs

FS/cs

FS

iii

Fig. 2. Zones and method of sample collection for the metallographic analysis. (a) S-Nw . Transversal cross section, tcs. Longitudinal cross section, lcs ; (b) S-Fr . Fracture surface, FS . Fracture surface cross section, FS/cs . Red lines i, ii and iii define the cutting planes.